Bivariate ENSO Timeseries
Calculated from combining a standardized SOI and a standardized Nino3.4 SST timeseries. Note that different SST dataset (Hadley SST) is now used to calculate Nino 3.4 timeseries. This replaces the GISST dataset. Most recent data is based on the NOAA OI V2 SST dataset.PSD

Tropical Northern Atlantic Index*
Anomaly of the average of the monthly SST from 5.5N to 23.5N and
15W to 57.5W. HadISST and NOAA OI 1x1 datasets are used to create index. Climatology is 1971-2000.
Enfield, D.B., A.M. Mestas, D.A. Mayer, and L. Cid-Serrano, 1999: How
ubiquitous is the dipole relationship in tropical Atlantic sea surface
temperatures? JGR-O, 104, 7841-7848.AOML and PSD

Oceanic Nino IndexIndex has been corrected to use the 3-month running mean version. Please download new version. From NOAA Climate Prediction Center (CPC). Three month running mean of NOAA ERSST.v2 SST anomalies in the Nino 3.4 region (5N-5S, 120-170W), based on changing base period which onsist of multiple centered 30-year base periods. These 30-year base periods will be used to calculate the anomalies for successive 5-year periods in the historical record:

Multivariate ENSO Index (MEI)* From PSD. Time series is bimonthly so the Jan value represents the Dec-Jan value and is centered between the months. Details and current values are at Dr Wolter's website. Reference: Wolter, K., and M.S. Timlin, 1998: Measuring the strength of ENSO - how does 1997/98 rank? Weather, 53, 315-324.

Northern Oscillation Index is an index of climate variability based
on the difference in SLP anomalies at the North Pacific High and near Darwin Australia. Schwing, F.B., T. Murphree,
and P.M. Green. 2002. The Northern Oscillation Index (NOI): a new climate
index for the northeast Pacific. Progress in Oceanography 53: 115-139.
The time series and more information are available.

(Updated to 2003) Monthly totals Atlantic hurricanes and named tropical stormsEach month has the total number of hurricanes or named tropical storms in that month in the Atlantic region. These values are from Unisys at http://weather.unisys.com/hurricane/atlantic/ who obtained them from Colorado State/Tropical Prediction Center. I computed the number of hurricanes that begin in each month. Note that the hurricane
might extend to the next month but won't be listed there. Their webpage should be read for a more complete description and attribution.

Note, values are now from CPC as they update their data
through the present
From CPC: The loading pattern of AO (AAO) is defined as the first leading mode from the EOF analysis of monthly mean height anomalies at 1000-hPa (NH) or 700-hPa (SH). Note that year-round monthly mean anomaly data has been used to obtain the loading patterns. Since the AO and AAO have the largest variability during the cold sesaon (variance of AO/AAO), the loading patterns primarily capture characteristics of the cold season patterns.
Daily and monthly AO (AAO) indices are constructed by projecting the daily and monthly mean 1000-hPa (700-hPa) height anomalies onto the leading EOF mode. Both time series are normalized by the standard deviation of the monthly index (1979-2000 base period). Since the loading pattern of AO (AAO) is obtained using the monthly mean height anomaly dataset, the index corresponding to each loading pattern becomes one when it is normalized by the standard deviation of the monthly index.Values and
description

(Definition slightly changed: old version available).The timeseries of SST anomalies averaged over 60W to 20W, 6N to 18N and 20W to 10W, 6N to 10N map. Data is obtained from the COADS dataset for 1951-1991 and NCEP afterwards. Anomalies were calculated relative to the 1951-2000 climatology, smoothed by three months running mean procedure and projected onto 20 leading EOFs. Month of data is the center of the 3 months that are smoothed. More information and the indexes forecasted values are available.

The timeseries of SST anomalies averaged over the the Caribbean. Data is obtained from the COADS dataset for 1951-1991 and NCEP after. Anomalies were calculated relative to the 1951-2000 climatology, smoothed by three months running mean procedure and projected onto 20 leading EOFs. More information and the indexes forecasted values are available.

Data is not being updated after Feb 2014. It is not known when or if it will be updated (due to resource issues)..Note that time series is scaled by 1e25. Values are 3-month running means except for the last month which is a 2-month average.

http://precip.gsfc.nasa.gov/ESPItable.html Please cite "ENSO Indices Based on Patterns
of Satellite-Derived Precipitation" Curtis and Adler in J. of Climate, 13,2786 (2000). Time series that uses rainfall data in the
Tropical Pacific to describe ENSO events.

http://jisao.washington.edu/data_sets/sahel/ From Mitchell:
The averaging region is based on the rotated principal component analysis of average June through September African rainfall presented
in Janowiak (1988, J. Climate, 1, 240-255). Stations within 20-8N, 20W-10E are obtained from the National Center for Atmospheric
Research World Monthly Surface Station Climatology (WMSSC), and 14 retained which had complete or almost complete records for
1950-93. See link for stations.

http://jisao.washington.edu/data_sets/brazil/
From Mitchell: The northeast Brazil rainfall index is calculated from data for Fortaleza (3.7S, 38.5W) and Quixeramobim
(5.3S, 39.3W) Brazil obtained from the NCAR World Monthly Surface Station Climatology.
Climatological mean is for 1950-79.